1. Field of Invention
The present invention generally relates to folding paperboard cartons and, more particularly, to an improved carton blank having novel caulking edges which define adhesive ports for superior sealing.
2. Brief Description of the Prior Art
Folding cartons are well known in the packaging art. Typical cartons and corresponding blanks are described in U.S. Pat. Nos. 4,712,689 and 4,712,730 which are incorporated by reference in this disclosure. These cartons are constructed from flat blanks which are pre-cut and pre-scored on paperboard sheets. Carton blanks have four main panels which are adapted to form the top, rear, bottom and front of an assembled carton. Each main panel has a pair of end flaps which are hingedly connected by score lines formed in the paperboard.
The blanks are folded once and secured with known adhesives to form carton sleeves which are used for packaging retail products, typically consumable goods. During the filling operation, packaging machinery is used to form and seal fully assembled cartons according to a prescribed folding sequence and adhesive pattern dependent on the carton design.
Most currently known carton sleeves have at least three overlapping flaps which require adhesive bonding for effective sealing and formation of end walls. U.S. Pat. No. 4,712,730 describes a state-of-the-art carton blank used to assemble a rectangular, top opening carton. First and second ends of the carton are closed by folding the bottom panel end flaps first; front panel end flaps second; top panel end flaps third and rear panel end flaps fourth and last.
Prior to folding in the fourth down flap, single lines of adhesive are deposited on the bottom panel end flaps. All four end flaps are secured by single glue lines to form a continuous wall at first and second ends of the carton. Commercial products of the type described in U.S. Pat. No. 4,712,730 are manufactured and sold by Fold-Pak Corporation, Newark, N.Y. under the HI TECH.RTM. and HI TECH PLUS.RTM. trade designations.
According to art-recognized techniques, adhesive attachment of the end-wall forming flaps is difficult to achieve because overlapping end flaps are not co-planar in the folded condition. In specific terms, the inner end flap is spatially removed from the outer end flap by portions of the intervening middle flap. This spatial separation is generally characterized by a single or double thickness of paperboard stock.
U.S. Pat. No. 4,872,609 addresses this problem by describing raised portions formed in the bottom panel end flaps of a typical carton blank. These raised portions are substantially triangular in shape and operably associated with cut-outs formed in the front panel end flaps of an assembled carton. According to this disclosure, the end wall-forming flaps are substantially co-planar so that fourth-folded rear panel end flaps are securely fastened to first-folded bottom panel end flaps with known adhesive patterns.
Carton blanks are typically produced on large paper-board sheets in a multiple configuration. During the blanking operation, score lines are provided to facilitate the flap-folding sequence. Perforations are also cut in the paperboard to form art-recognized tear-away and breakaway features like those described in U.S. Pat. No. 4,712,689. Perforations and score lines are formed by die-cutting and die-stamping the carton blanks in a single, downward direction.
The offset portions of the prior art are raised from the bottom panel end flaps of a carton blank. They are formed in the paperboard stock by stamping the carton blanks in an upward, opposite direction with reference to the score lines and perforations. This procedure involves a reverse die-stamping operation which requires special make ready procedures and additional expense. The presently claimed invention eliminates the need for offset portions and introduces novel improvements which solve the problems existing in the art.